Recent studies conducted in the United States found that green certified homes sold for up to 30% more on average.
An article in the August 2011 edition of ECOHOME reports on several studies which found that green homes not only sold for a premium but also sold faster than more conventional homes. Although the studies are based on averages, the research notes a consistent trend even while home sales in general were down: Third-party certification results in a higher sales price.
To read the whole article:
http://www.ecohomemagazine.com/news/2011/08-august/green-homes-sell-for-more-studies-show.aspx